1. Field of the Invention
The present invention is directed to a system for optimizing the allocation of downpeak elevator traffic in an elevator group.
2. Discussion of the Background Information
During evening rush hours, heavy elevator traffic occurs in which the elevators cars generally fill up at the upper floors and bypass the lowers floors. Thus, down floor call waiting times in the lower floors rise dramatically.
To equalize service among the upper and lower floors, some elevator control systems utilize a computer controlled dispatch strategy to allocate elevator traffic according to a time based algorithm. One example of such a time based algorithm strategy is shown in U.S. Pat. No. 4,492,288, the disclosure of which is incorporated by reference in its entirety. In the '288 patent, down hall calls are combined to form groups based upon a somewhat chronological order of inputted hall calls. The down hall calls are stored in a RAM in chronological order. The oldest call is allocated to a highest priority elevator car and the next oldest call is allocated to either the highest priority elevator car or to a second priority car, depending upon the specific situation.
Another system for allocating down hall calls is shown in U.S. Pat. No. 5,480,006. During a downpeak period, this system gives priority service to down travelling traffic and reserves at least one elevator car for up service. However, all floors requiring down service are given equal access to the system regardless of the floor position in relation to the building. The system divides the building into a number of sectors equal to the number of cars available for downpeak. Any remaining floors are redistributed to the lower. A particular sector is assigned to a car depending upon the age of the sector. Once the sector is assigned, the car parks at the top of the sector until a down hall call is made and serves the down hall calls from highest to lowest.
However, even utilizing the above noted strategies, high average waiting times still exist due to the corresponding poor distribution of elevators throughout the building.